Lectins are proteins with binding sites that recognize a specific sequence of sugar moieties in complex glycoconjugates. In the present study the tomato lectin ­ Lycopersicon esculentum (LEL) (a selective microglial and endothelial marker) has been reported to recognize specific residues of N-acetylglucosamine (GlyNAc) and poly-N-acetyllactosamine. In the pineal gland the biotinylated LEL was used to investigate the appearance of these sugar residues in the structures of the rats during their development and adult life. Our results showed that the binding of LEL occurred exclusively in the material adherents on surface of the endothelia of the vessels in the peripheral and central regions of the gland. An exception can be cited to rats in first postnatal day where the vessels in the central region did not display the LEL-reaction. In all animals studied and, from 3- postnatal day onwards the LEL-reactions could be observed within the central space of pseudo-rosettes also characterizing this space as a vessel